Since Typo3 version 10.4.19 the template Book\Show.html and partial Book\CartForm.html shows code as text where the source contains inlinescript.
source:
<script type="application/ld+json"> <cartbooks:schema book="{book}" /> </script>

output:
<script type="application/ld+json"> {"@context":"https:\/\/schema.org","@type":"Book","additionalType":"Product","name":"Das Neue Frankfurt und die Frankfurter K\u00fcche","author":"Klemp, Klaus\/\/ Wagner K, Matthias (Hrsg.)","offers":{"@type":"Offer","price":20,"priceCurrency":"EUR"}} </script>

and complete partial:
<f:render partial="Book/CartForm" arguments="{book: book, pid: cartSettings.cart.pid}" />

output:
<form data-ajax="1" data-type="book" data-id="40" method="post" class="add-to-cart-form" id="book-40" action="/shop/warenkorb?tx_cart_cart%5Bcontroller%5D=Cart%5CProduct&type=2278001&cHash=66f49eddf86d8b5a3a21ced72ba10fb5"> <div> <input type="hidden" name="tx_cart_cart[__referrer][@extension]" value="CartBooks"> <input type="hidden" name="tx_cart_cart[__referrer][@controller]" value="Book"> <input type="hidden" name="tx_cart_cart[__referrer][@action]" value="show"> <input type="hidden" name="tx_cart_cart[__referrer][arguments]" value="YToxOntzOjQ6ImJvb2siO3M6MjoiNDAiO30=fc1d475bdb7f72ad93388f1fdfcceba9163f79e0"> <input type="hidden" name="tx_cart_cart[__referrer][@request]" value="{"@extension":"CartBooks","@controller":"Book","@action":"show"}935e372ffa40f4d0415ed71552057219f1bea5ad"> <input type="hidden" name="tx_cart_cart[__trustedProperties]" value="[]a2131fde6bb13aaaec0ca019f36e0351396f5b34"> </div> <input type="hidden" name="tx_cart_cart[productType]" value="CartBooks"> <input type="hidden" name="tx_cart_cart[book]" value="40"> <input class="form-control" type="number" min="1" step="1" value="1" name="tx_cart_cart[quantity]"> <input type="submit" class="form-control btn btn-default" value="in den Warenkorb"> <div class="form-message" data-ajax-message-timeout="3000"> <div class="form-success" style="display: none;" data-ajax-success-block> <div class="alert alert-success" data-ajax-success-message></div> </div> <div class="form-error" style="display: none;" data-ajax-error-block> <div class="alert alert-warning" data-ajax-error-message></div> </div> </div> </form>

All that I could find out is that with the version 10.4.19 changes happened concerning feature #91132.
See https://docs.typo3.org/c/typo3/cms-core/main/en-us/Changelog/10.4.x/Feature-91132-IntroduceUserSettingsJavaScriptModulesEvent.html